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Would appreciate opinions on system recommended for new 5200 sq ft home in Chicagoland area where system would get average to above average use... Builder included (3) Carrier 93% HVAC 10 SEER (2 first floor, 1 second floor) with motorized zoned-damper systems and separate controls for each system. Also is 10 SEER still being used? Can replacement parts be obtained? Thanks!!

Confusing the subs

When you spec the "lowest of the low" for AC equipment, how are you going to communicate to the guy who installs the ductwork that you want THAT part done really well?

Because you NEED good ductwork in order for any system to perform well. The actual idea of 10 SEER doesn't bug me if only it were installed well. I am a homeowner in S.Texas and know the economics of high SEER is questionable, and that you run far fewer hours in a year than we do. But if the sub-contractors see bottom of the line AC equipment, won't they think you will accept bottom of the line ductwork too?

In the absence of a guru right this minute, I suggest you might spec a maximum ESP (External Static Pressure) for your system at a given airflow. Don't just ask for passable (I have .50-.60 sometimes, wish it were .40) but try to get yourself a margin of safety. So many of the crappy duct designs I know of, have the symptom of a too-high ESP. I would like to ask the actual gurus whether this idea is workable, and if they would second the idea.

I have seen bids which guarantee a certain level of humidity so this would appear not to be too much to ask.